During the past year we have continued our work applying rapid MRI to guide simple and complex mechanical and biological interventions. We continue to employ MRI catheterization as standard clinical practice at the NIH clinical center, based on our earlier careful pilot research comparison of conventional X-ray and wholly MRI guided transfemoral pulmonary artery catheterization in adults. We continue to enhance the capabilities of MRI catheterization to characterize heart function in patients. We have taught two dozen medical centers across North America and Europe how to adopt these techniques by hosting hands-on workshops in our labs at NIH. This year we performed the first human cardiovascular guidewire catheterization using the new low-field and high-performance cardiovascular MRI system at 0.55T. We have developed a completely new approach to treat heart rhythm disorders by injecting small amounts of acetic acid (vinegar) rather than conventional electrical burning (radiofrequency ablation). This new chemoablation approach provides targeted irreversible destruction of small amounts of electrical tissue in a way far more promising than conventional techniques. We are working on more sophisticated catheters, and on development of acetic acid as a drug, for testing on patients. Overall we have successfully developed novel applications of real-time MRI for cardiovascular treatments, and we continue to work to clinical applications of these exciting new developments.